Xerographic plate

ABSTRACT

A xerographic plate including a mandrel and a photoconductive sleeve mounted thereon. The mandrel has an inflatable tube mounted in a groove for securing the sleeve to the mandrel.

United States Patent Gregory 1 1 XEROGRAPHIC PLATE [72] Inventor: PaulM. Gregory, Cheltenham, En-

gland [73] Assignee: Xerox Corporation, Rochester, NY. [22] Filed: Feb.13, 1970 [2]] Appl. No.: 11,160

[52] US. Cl. ........................355/3, 101/378, 269/22, 294/63 A[51] Int. Cl. ..G03g 15/00 [58] Field of Search ..3$S/3, 16, 85, 87, 92;279/1 D; 269/22; 101/375, 378; 294/93, 99, 63 A [56] References CitedUNITED STATES PATENTS 2,987,994 6/ 1961 Allison ml/Q76 45] Oct. 3, 19723,253,854 5/1966 Hollander, Jr. ..269/22 X 3,379,527 4/1968 Corrsin eta]. ..355/17 X 4 3,166,335 1/1965 Mason .294/93 X FOREIGN PATENTS ORAPPLICATIONS 109,212 9/1917 GreatBritain Primary Examiner-Samuel S.Matthews Assistant Examiner-Richard M. Sheer Attorney-James J. Ralabate,Norman E. Schrader and Michael J. Colitz, Jr.

[ ABSTRACT A xerographic plate including a mandrel and a photooonductivesleeve mounted thereon. The mandrel has an inflatable tube mounted in agroove for securing the sleeve to the mandrel.

PATENTEDUCI a 1972 3. 695. 757

INVENTOR. PAUL M. GREGORY BY 5n.

ATTORNEY XEROGRAPI-IIC PLATE This invention relates to a cylindricalsupport for a sleeve. One particular application is a cylindricalsupport for a sleeve having an outer surface of photoconductivematerial.

In xerographic copying machines, the xerographic plate is often in theform of a drum. The drum has a rigid cylindrical body mounted on anaxial shaft, and a photoconductive insulating layer is overcoated on thebase. The layer has a conductive base, which may be provided by the drumbody. This photoconductive layer is liable to damage and ageing effects,and the recoating of such drums is troublesome.

It has been proposed to form the photoconductive layer on a flexiblesleeve and to mount the sleeve on a separate cylindrical mandrel whichcan be contracted so that the sleeve can easily be fitted on the mandreland then expanded to hold the sleeve in an accurately cylindrical shape.Such a mandrel has been proposed using a hollow cylinder with a slotextending parallel to the axis and a cam operated linkage for openingand closing the slot. Such a cylinder has proved difficult tomanufacture, and the present invention can be used to provide analternative support for such a sleeve.

According to the invention there is provided a cylindrical support for asleeve, wherein the periphery of the support can be altered from acontracted state to an expanded state, the support comprising a rigidcylinder whose outer surface is formed with at least one grooveextending in a generally circumferential direction, and a hollow bodywhose shape depends on the difference of its internal and externalpressure lying in the trough of the groove, the body being movable bychange of in ternal pressure between a first state in which the bodylies within the outer surface of the cylinder and a second state inwhich the body extends beyond the periphery of the rigid cylinder toexpand the periphery of the support foundation for a sleeve on thecylinder.

An example of the invention will be described with references to thedrawings in which FIG. 1 is a perspective view of a sleeve and acylindrical support with its inflatable body removed.

FIG. 2 is an end view showing the clamped end of a tube.

FIG. 3 is a view of the opposite end to FIG. 2, showing a valve at theother end of the tube.

FIG. 4 is a sectional view through line 4-4 of FIG. 3 and FIG. 5 is asectional view similar to that of FIG. 4 but showing a modified grooveand tube.

In the drawings, the outer surface of a hollow metal cylinder or mandrell l is fomied with a circular groove 12 which is five-sixteenths incheswide and three-sixteenths inches deep at each end, with a helical grooveI3 running between the end grooves with a pitch of five-sixteenthsinches and being three-sixteenths inches deep. Within the helical groovea rubber tube 21 is carried, shown in FIG. 4 but not shown in FIG. I. Asshown in FIG. 4, the tube 21, when in a non-inflated condition, issubstantially enclosed within the trough of the grooves provided so thatthe outer periphery of the tube is supported below the outer surface ofthe cylinder 11. On each end of the helical groove the tube passesthrough a hole in the cylindrical shell to the interior of the cylinder.One end of the tube is closed by clamp 19 on cylinder 11 (see FIG. 2)and the other end is connected to a valve, 14, seen in FIG. 3.

At each end of the cylinder. there is provided an internal flange 15from which extend three spokes 16, supporting an axial bearing 17, sothat the drum may be mounted on a shaft for rotation about its axis.

A flexible cylindrical sleeve 18 including a photoconductive insulatinglayer coated on a conducting layer is to be mounted on the drum. In theFIG. I embodiment, the rubber tube normally does not protrude beyond thetop of the groove, so that when the sleeve is made with an internaldiameter slightly greater than the external diameter of the drum, thesleeve can easily be slipped over the drum. The difference in diameterof the cylindrical shell and the inside of the sleeve is about 0.004inches. The sleeve is held in its required position on the drum, and airis introduced through the valve 14 into the tube so that the tubeexpands to extend above the periphery of the drum and to exert pressureon the inside of the sleeve to hold it in an accurate cylindrical shapeon the drum to constitute the xerographic plate. When the sleeve is tobe removed, the air is released from the valve to deflate the tube.

In order to permit the photoconductive properties of the sleeve 18 to beeffective during xerographic operations as described in US. Pat. No.3,30l .126 to Osborne et al., the sleeve is grounded. This is achievedthrough a conductive member 20 such as a metal grounding wire bolted,clipped or otherwise secured between the conductive layer of the sleeveand the metal cylinder 11. The cylinder is grounded through itssupporting shaft in the conventional fashion.

In an alternative embodiment, the tube normally extends above thecylindrical surface of the drum, but can be contracted into the tube byreduction of the pressure within the tube. In this case, the valve 14normally acts to allow air out of the tube, the valve is connected to asource of reduced pressure in order to reduce the size of the tube toallow the sleeve to be placed in position and removed, and air isallowed back into the tube at normal atmospheric pressure to secure thesleeve on the drum.

A pressure differential of a few pounds per square inch is believed tobe sufficient to change the shape of the tubes to secure and release thesleeve. A length of tube of feet could be used on a 9 inch diameterdrum.

As shown in FIG. 5, the circular grooves 22 and the helical groove 23could be rectangular in cross-section and the tube 24 could berectangular. In such case it would be desirable to make the tube withthicker walls 25 at its bottom and sides than at the top 26 where itmust expand to effect the holding of the sleeve.

A pump may be provided within the drum to force air into or out of thetube in accordance with any of the embodiments described above.

In some applications, a plurality of tubes could be mounted in groovesin the cylinder. The tubes could be connected together to receive thesame pressure or different pressures could be applied to different tubesto achieve a desired expansion pattern. Inflatable pads in suitablyshaped recesses may also be used.

While the instant invention has been described herein with reference tothe structures disclosed, it is not intended to be so limited and thisapplication is in- 3 4 tended to cover such modifications or changes asmay to freely move said mandrel, come within the scope of the appendedclaimsmeans to inflate said inflatable member to expand hat is C m is;said member into contact against the sidewalls of l. A xerographic drumsuitable for use in an autothe groove and to expand a portion of said ifl matic xemgraphic reproducing apparatusincluding 5 ble member beyondthe outer diameter of said a flexible cylindrical sleeve formed of anelectrically conductive substrate having a layer of photoconductivematerlal f i a flexible conductive member for electrically cona supportmandrel having an outside diameter that is fleeting the substrate ofsaid sleeve to said mam slightly less than the inside diameter of theflexible dreL cylinder whereby said support mandrel is capable ofsupporting said cylinder in free sliding relation- F surface manfirelsaid inflatable member comprises aflexible tube. having a continuousgenerally circumferentially extending helical groove formed therein Theapparatus of (ilaim l h i said groove is a sin e inflatable membersitioned vmhin said rectangular in cross section and said Inflatablemember groive said member beingpglbstamiauy endosed is rectangular incross section and the wall of said tube within said groove with theouter periphery of said adjacent the penpheral. s,urface of Sam W memberbeing below the outer surface of said thinner than the remaining wallsof said flexible mandrel when said member is in a non-inflated member'condition to allow said flexible cylindrical sleeve mandrel into holdingcontact against said sleeve, and

2. The apparatus of claim I wherein said helical groove is generallysemi-circular in cross section and

1. A xerographic drum suitable for use in an automatic xerographicreproducing apparatus including a flexible cylindrical sleeve formed ofan electrically conductive substrate having a layer of photoconductivematerial placed thereover, a support mandrel having an outside diameterthat is slightly leSs than the inside diameter of the flexible cylinderwhereby said support mandrel is capable of supporting said cylinder infree sliding relationship thereon, the outer surface of said mandrelhaving a continuous generally circumferentially extending helical grooveformed therein, a single inflatable member positioned within saidgroove, said member being substantially enclosed within said groove withthe outer periphery of said member being below the outer surface of saidmandrel when said member is in a non-inflated condition to allow saidflexible cylindrical sleeve to freely move said mandrel, means toinflate said inflatable member to expand said member into contactagainst the sidewalls of the groove and to expand a portion of saidinflatable member beyond the outer diameter of said mandrel into holdingcontact against said sleeve, and a flexible conductive member forelectrically connecting the substrate of said sleeve to said mandrel. 2.The apparatus of claim 1 wherein said helical groove is generallysemi-circular in cross section and said inflatable member comprises aflexible tube.
 3. The apparatus of claim 1 wherein said groove isrectangular in cross section and said inflatable member is rectangularin cross section and the wall of said tube adjacent the peripheralsurface of said mandrel is thinner than the remaining walls of saidflexible member.